JAVA獲取每個月的天數

            String month = vo.getM_MONITORMONTH();
            int year = Integer.parseInt(month.substring(0, month.indexOf('-')));
            int mth = Integer.parseInt(month.substring(month.indexOf('-')+1));
            Calendar calendar = Calendar.getInstance(); 
            calendar.clear();    //在使用set方法之前，必須先clear一下，否則很多信息會繼承自系統當前時間
            calendar.set(Calendar.YEAR,year);   
            calendar.set(Calendar.MONTH,mth-1);  //Calendar對象默認一月爲0          
            int endday = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);//獲得本月的天數